new tasks

Task/Balanced_brackets/Lua/balanced_brackets.lua

@@ -0,0 +1,20 @@
+function isBalanced(s)
+  --Lua pattern matching has a 'balanced' pattern that matches sets of balanced characters.
+  --Any two characters can be used.
+  return s:gsub('%b[]','')=='' and true or false
+end
+
+function randomString()
+  math.randomseed(os.time())
+  math.random()math.random()math.random()math.random()
+  local tokens={'[',']'}
+  local result={}
+  for i=1,8 do
+    table.insert(result,tokens[math.random(1,2)])
+  end
+  return table.concat(result)
+end
+
+local RS=randomString()
+print(RS)
+print(isBalanced(RS))